The X Prize for Cars.

There already is a car which is essentially is satisfying the basic criteria.

If mass produced the cost would be viable for the public.

http://www.teslamotors.com/index.php?js_enabled=1

42 km/L is about 2.4 L/100km. I want a car that does 1L/100km, or 100km/L.

Americans will learn in the next generation or so that their lifestyle is unsustainable. There are suburbs and exurbs being built today which will resemble third world countries in 50 years because their location (far, far out and away from any work center) is unsustainable with rising gas prices. We're talking cooking over empty oil drums here.

Public transit, not fancy 100mpg one or two seaters (no one can afford anyway) and a life-style adjustment are what is needed, sadly we're behind the rest of the developed world in all these parts and this bodes badly for our future as a nation.

Instead of squandering $500 billion on the war (so far) we really could have used that money to replace (yes, get rid of, and build new) Amtrak and link America's cities by high speed rail, not unsustainable super highways.

Until the 49% of Americans who have never used public transit, think buses and bicycles are for poor people, and have the insane need to "feel safe" in their hulking SUVs get on board with the rest of us things are going to get a lot worse before they get better.

100 mpg & pass even tough Federal Tier II and California ULEV standards is fairly easy if the vehicles don't have to meet safety standards and be large enough to be sellable in volume on the market. Sure, somebody will come up with a 1 behind the other 2 seater that weighs 900# and gets 120 mpg on the Federal test. Big deal... You can't sell it if it doesn't pass crash standards. These keep getting tougher, and automakers respond by adding to the structure every design cycle. That's why even a "MINI" today weighs close to 3000 lbs -- twice (!!!) the weight of the original Mini. It's a whole lot more impressive if somebody comes up with a practical high mpg vehicle that they actually believe there is a market for, and are willing to risk their own capital to develop for sale. Do that, and then I will be impressed.